British High Commissioner to Canada Susan le Jeune d'Allegeershecque speaks to Prime Minister Justin Trudeau during their first meeting in August. (Susan le Jeune d'Allegeershecque/Twitter)

The new British High Commisioner to Canada said the U.K. is open to the so-called progressive chapters the Liberal government has been pushing for in free trade deals, but not right off the bat.

Prime Minister Justin Trudeau and his British counterpart Theresa May told reporters they agreed to a "seamless" transition of the Comprehensive Economic and Trade Agreement (CETA) between the European Union and Canada after the U.K. leaves the EU and is no longer a party to that agreement.

May said her government will be putting together a "working group" with Canada on a new trade deal, with CETA as the basis.

"I think initially what we're looking for is a more or less a direct transposition of what's there already. But as both prime ministers made clear on Monday, that doesn't exclude the possibility after we've left the European Union to re-examine the agreement and add or substract things from it," said Susan le Jeune d'Allegeershecque.

Speaking at the Atlantic Council Global Citizen Awards Gala in New York City Tuesday, Trudeau reiterated the importance of pushing chapters on gender equality, Indigenous rights, and labour protections as priorities for a new North American Free Trade Agreement.

He said trade deals have been broadly positive for the majority of citizens, but if they were perfect there would be no populist backlash like the ones currently occurring, especially in former manufacturing regions slammed by offshoring and automation.

"In short, progressive trade is not a frill. In addition to being the right thing to do, it is a practical necessity, without which popular support for a growth agenda cannot be maintained," Trudeau said.